Electric motors convert electrical energy to mechanical energy to drive rotary machines, such as centrifugal gas compressors. The electric motor and the rotary machine can be assembled into a single housing. This integrated system, or integrated machine, may be more compact than a separate electric motor and rotary machine system. The rotating parts of any rotary machine have resonance frequencies, where such rotating parts, for example, a drive shaft, can physically bend. The bending shape of such a rotating part at such a resonance frequency is referred to herein as a mode. If left uncontrolled, modes can present a destructive force to both the electric motor and the rotary machine.
The present disclosure is directed toward overcoming one or more problems discovered by the inventors or that is known in the art.